Organic electroluminescent devices can utilize organic small molecules or polymers that produce light when transferred into their excited state by an external power source. The excited state is created when positive and negative charges flow from opposite electrodes into the electroluminescent materials. Frequently, in multi-layer devices, hole injection and/or hole transport materials between one electrode and the electroluminescent material improve the efficiency of the device. These devices are being designed for use in, for example, monochrome and colored flat panel displays, signage, and white lighting. With increasing commercial demands, however, better devices are needed which have better materials suited for particular application and which can be tailored, commercially made, and provide good stability.
WO 2005/081335 (Gambogi et al., DuPont) describes multilayer devices including charge transport layers and processing methods.
EP 1,279,691 (Heeney et al., Merck) describes fluorinated semiconducting materials.
US Patent Publication 2005/0080219 (Koller et al.) purportedly describes methods of making polythiophenes.
U.S. Pat. Nos. 6,602,974 and 6,166,172 to McCullough et al. describe regioregular polythiophenes including homopolymers and block copolymers.
A need exists for better control over the synthesis of new materials for particular device applications including both the doped and undoped states.